Thursday, October 25, 2018

How Could the Continent of South America Have Been an Island During Nephite Times? – Part II

Continued from the previous post, regarding the mountain building in South America, and results of new scientific studies and findings, as well as the continuation of the two questions raised by a reader.
    In two recent but separate pioneering studies using methods of measuring ancient mountain elevations, both showing “results that are in tight agreement,” that the Andes Mountains have grown several times faster than geologists have always thought (“Mountain Ranges Rise Dramatically Faster Than Expected,” Science Daily, Science News, Janaury 26, 2006; Carmala N. Garzione, et al., “Tectonic Evolution of the Central Andean Plateau and Implications for the Growth of Plateaus,” Earth and Planetary Science Letters, Annual Review, vol.45, Elsevier Journals, 2017, pp529-559).
Sedimentary deposits near Cerdas in the Altiplano plateau of Bolivia, where rocks contain ancient soils used to decipher the surface temperature and surface uplift history of the southern Altiplano

It might also be of interest to note that until Camala Garzione's research, geologists estimated surface uplift by examining leaf fossils to determine at what elevation the plants lived, or by dating when certain minerals began moving rapidly to the surface. Unfortunately, as Garzione has pointed out, plant characteristics can change radically over time, and changes in climate can also cause erosion, throwing a significant question mark into the equation. Stated differently, determining ages of mountains in the past was, at least in part, a guessing game.
    As an example, according to Garzione, "People have largely ignored the role of the mantle lithosphere because it is difficult to look 50 to 200 kilometers [31 to 125 miles] into the earth; whereas we can easily see the deformation on the surface."  See the last post for details on this issue.
    Regarding the past, she adds, "Some geologists have guessed that the mantle lithosphere is removed continuously and evenly during mountain building. Our data argue that the mantle just accumulates down there until some critical moment when it becomes unstable and drops off." This is a considerably important factor, first that geologists had guessed at something in the past, and that her studies show the past thinking was completely erroneous as to how mountains grew upward—not slowly and gradually in extensive time periods, as they believed, but in short “growth spurts” quite suddenly, as she and her team pointed out.
    It also might be of interest to note that this theory has been around since the early 1980s (38 years ago), but it did not stand up to the scrutiny of mainstream science, because the techniques necessary to estimate surface elevation have only been recently developed.
The eclogite anchor keeps the crust from rising as it pulls the lithosphere downward. When the anchor is heavy enough to break free, the lithosphere rebounds upward, elevating the hill or mountain
It should be noted that, according to Garzione “the Altiplano plateau in the central Andes—and most likely the entire mountain range—was formed through a series of rapid growth spurts.” This dove-tails well into the fact that at the time of the Crucifixion, there were mountains in the Land of Promise, and while some fell and others were lifted up, no doubt some that existed came up to even higher levels. As Garzione added, “The Altiplano could have rocketed up so quickly only if something heavy, like an eclogite anchor, dropped off its bottom.”
    On the other point in the critique from a reader, the early size of South America was impacted by the geologic understanding that most of South America was anciently submerged except for the Andean Shelf along the west coast, the three cratons or shields (Brazilian, Guiana, and Rio de la Plata)—generally a large area of exposed crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas of the continental crust that rise high from the stable craton from which they extend.
Early geologic makeup of South America, showing the Andean Shelf and two major Shields, of which parts were above the submerged Amazonian Basin, forming the two major seas, two seaways, and the Amazon Sea extending along the current river pass between the shields

Magmatic arcs are offshore volcanoes that form islands that results in a volcanic island arc. Generally, and in the case of the western coastal area of South America, a volcanic arc resulted from the subduction of the Nazca and Antarctic tectonic plates beneath the South American tectonic plate, parallel to the Peruvian-Chilean deep oceanic trench along the coast. The volcanic arc of a chain of volcanoes along the South American west coastal mountains of the Andes, formed above this subducting plate, with the oceanic plate saturated with volatiles such as water that drastically lowered the melting point of the mantle. Thus, as the oceanic plate was subducted, it was subjected to greater and greater pressures with increasing depth. This pressure squeezed the water out of the plate and introduced it to the mantle melting the mantle and forming magma at a depth under the overriding plate. The magma ascends to form an arc of volcanoes along the Andean Volcanic Belt parallel to the subduction zone, of which there are currently 174 active volcanoes.
    According to Víctor Alberto Ramos, an Argentine geologist who has contributed to the paleogeography and plate tectonics of South America, claims that the Andean Uplift and the Andean orogeny were characterized by extensional tectonics, rifting, the development of back-arc basins and the emplacement of large batholiths—a large mass of intrusive igneous rock larger than 40 square miles, and made mostly of granite, quarta monzonite or diorite .
The earlier land of Chilenia showing the morphostructural units of the Andes between 28°S and 36°S latitude, the inferred boundary between exotic Chilenia and Cuyania terranes; showing Lehi’s landing site of Coquimbo Bay/La Serena west of the Principal Cordillera and the eventual coast line (gray dotted line)

Ramos, incidentally, was the first to recognize the existence of Chilenia and the former sea that separated it from the rest of South America. At the time of the discovery in the 1980s it was considered to be speculative. In a 1988 conference in Chile the discovery of Chilenia was not well received and many at the conference made ridicule of him; however, as the existence of Chilenia was finally recognized the discovery made him later a member of the Chilean Academy of Sciences (Víctor A. Ramos, “Anatomy and Global context of the Andes: Main geologic features and the Andean Orogenic cycle,” The Geological Society of America Memoir, vol.204, GeoScience World, McLean Virginia, 2009, pp31–650).
    According ot Adrian Hartley, palaeoaltitude data suggest that a substantial proto-Central Andean mountain range was in place anciently, and that the data support the idea that therefore the Andean rain shadow also existed which reinforced the pre-existing climatic regime rather than changing it. The change to hyperaridity in western South America is attributed to a combination of global climate cooling and enhanced upwelling of the Humboldt current generated by closure of the Central American Seaway and not to the Andean rain shadow (Adrian J. Hartley, “Andean Uplift and climate Change,” Journal of the Geological Society, Lyell Collection, vo.160, 2003, pp7-10).
    All of this, and what is to follow, is meant to show those who have difficulty in getting their minds around ideas such as this that are not in the mainstream of the public conscience (think of the difficulty Joseph Smith and the early Saints had in convincing people of ideas so different than that of all other religions of the time). The point is that South America, like all other lands on this earth do not date back much before 13,000 years according to the Biblical account, and even was dated as such with the initial test of Libby’s C-14 time clock before he changed the basis, was until the crucifixion of Christ as large island running along the Andean Shelf on the west coast of South America, a long, narrow island, in which Lehi landed in the far south and Nephi traveled some distance northward to settle and build his temple and where the Nephites populated for some four hundred years before Mosiah moved farther northward.
    However, there is more to understand about the geologic formation of South America, and the Andean Uplift.
(See the next post, “How Could the Continent of South America Have Been an Island During Nephite Times? – Part III, for more on how South America was formed, why it was an island along with a handful of mastiffs and shields, and when and how this changed)

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